In the construction of typewriter carriage actuating mechanisms it has been usual to employ as the carriage driving force a relatively long coiled spring or an encased spiral spring of the clock-spring type, relatively complex escapement and pawl means being used, in conjunction with ratchet teeth on the carriage, to control the movement of the carriage by the spring. Such arrangements have required very precise and delicate adjustments of a pair of pawls or the like, one of which is used to release the carriage for a partial movement, amounting to less than one full tooth, under the influence of the spring, and the other pawl functioning to arrest and hold the carriage in the desired position after one full tooth has passed. The prior art mechanisms referred to are not only relatively expensive and delicate, but render it difficult to maintain highly accurate positioning of the carriage, particularly after wear has occurred. In addition, blurred impressions are sometimes created due to slight movement of the carriage while the type bar is striking the paper.
The present invention aims to provide an improved carriage-actuating mechanism wherein the carriage is accurately moved through a distance of one full tooth, by a pawl, no carriage return spring being required, the arrangement being such that any wear which occurs between the pawl and ratchet teeth cannot interfere with proper operation of the mechanism.
A further object is to provide such a mechanism which is simple, rugged and inexpensive, and which permits movement of the carriage in either direction without damage to the parts by force applied directly thereto without the necessity of releasing pawl or escapement components from engagement with the ratchet teeth.
Another object is to provide such a mechanism in which forward movement of a type bar does not cause any movement of the carriage, and in which all movement of the carriage occurs during the return stroke of the type bar, a full, exact and uniform movement being assured, so that blurring does not occur, and the carriage can always be returned accurately to any previous position.
Another object is to provide such a mechanism which is particularly suitable for toy typewriters and which, by achieving both lower cost and better performance, makes it possible to sell such machines, which have a high educational value, at lower cost to the purchaser.
Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.